Microbes: Invisible Invaders 

How Microbes Make Us Sick

Microbes live everywhere on Earth. They can be found in food, air, soil, water, saliva, a doorknob or hypodermic needles. But once inside our bodies, some microbes can make us sick.

Viruses can make us sick when they infect our cells and turn them into virus factories. Bacteria, protozoa and fungi regularly live harmlessly in and on the body. But sometimes, these microbes start colonies in areas of the body where theyre not used to living. That makes us sick. Other times, normally harmless bacteria produce poisons. Those poisons kill cells and cause illness.

How the Body Defends itself Against Illness

Our bodys immune system has many defense weapons to fight disease.

Skin is our first line of defense. This tough barrier keeps most microbes from entering our bodies.

Our stomach and intestines produce strong acids and enzymes that kill most of the microbes that we swallow.

One of the tasks carried out by special molecules called hormones molecules are the smallest unit of matter, formed by groups of atoms is to stir up and deploy our immune system forces.

Antibodies are the immune systems advance scouts. They are Y-shaped molecules that travel through the body looking for invading microbes. When they find them, they grab them and disable them.

White blood cells are the immune systems big guns. Alerted by antibodies, they track down the invading microbes and destroy them.

Invading microbes produce negative effects, but our immune system defenses also cause symptoms of disease. For example, the stuffy nose and sneezing of the common cold is a result of the immune system flooding the area with potent microbe-fighters. The symptoms tell us that a cure is on the way. 

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